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><H1
><A
NAME="SQL-UNLISTEN"
></A
>UNLISTEN</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN76063"
></A
><H2
>Name</H2
>UNLISTEN&nbsp;--&nbsp;stop listening for a notification</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN76068"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>UNLISTEN { <TT
CLASS="REPLACEABLE"
><I
>channel</I
></TT
> | * }</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN76071"
></A
><H2
>Description</H2
><P
>   <TT
CLASS="COMMAND"
>UNLISTEN</TT
> is used to remove an existing
   registration for <TT
CLASS="COMMAND"
>NOTIFY</TT
> events.
   <TT
CLASS="COMMAND"
>UNLISTEN</TT
> cancels any existing registration of
   the current <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> session as a
   listener on the notification channel named <TT
CLASS="REPLACEABLE"
><I
>channel</I
></TT
>.  The special wildcard
   <TT
CLASS="LITERAL"
>*</TT
> cancels all listener registrations for the
   current session.
  </P
><P
>   <A
HREF="sql-notify.html"
>NOTIFY</A
>
   contains a more extensive
   discussion of the use of <TT
CLASS="COMMAND"
>LISTEN</TT
> and
   <TT
CLASS="COMMAND"
>NOTIFY</TT
>.
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN76084"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="REPLACEABLE"
><I
>channel</I
></TT
></DT
><DD
><P
>      Name of a notification channel (any identifier).
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>*</TT
></DT
><DD
><P
>      All current listen registrations for this session are cleared.
     </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN76097"
></A
><H2
>Notes</H2
><P
>   You can unlisten something you were not listening for; no warning or error
   will appear.
  </P
><P
>   At the end of each session, <TT
CLASS="COMMAND"
>UNLISTEN *</TT
> is
   automatically executed.
  </P
><P
>   A transaction that has executed <TT
CLASS="COMMAND"
>UNLISTEN</TT
> cannot be
   prepared for two-phase commit.
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN76104"
></A
><H2
>Examples</H2
><P
>   To make a registration:

</P><PRE
CLASS="PROGRAMLISTING"
>LISTEN virtual;
NOTIFY virtual;
Asynchronous notification "virtual" received from server process with PID 8448.</PRE
><P>
  </P
><P
>   Once <TT
CLASS="COMMAND"
>UNLISTEN</TT
> has been executed, further <TT
CLASS="COMMAND"
>NOTIFY</TT
>
   messages will be ignored:

</P><PRE
CLASS="PROGRAMLISTING"
>UNLISTEN virtual;
NOTIFY virtual;
-- no NOTIFY event is received</PRE
><P></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN76112"
></A
><H2
>Compatibility</H2
><P
>   There is no <TT
CLASS="COMMAND"
>UNLISTEN</TT
> command in the SQL standard.
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN76116"
></A
><H2
>See Also</H2
><A
HREF="sql-listen.html"
>LISTEN</A
>, <A
HREF="sql-notify.html"
>NOTIFY</A
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